where can i find a good deal on 20" Staggered rims

[kashmir]

I drive a 2005 x5 4.4 with 1000 miles on motor and 80k on the rest. I have been thinking upgrading to 20" rims. I did some research on this forum and decided to go with 20' staggered rims in black. I, however, dont want to pay the showroom price. I have been looking at craigslist and have found some good options. I contacted a couple with "would these fit my x5"...answer was " yes but check with the dealer".

i know my bolt pattern is 5 x120. What else do I need to know when i look at rims that came off non-bmw cars or non-x5 bmw models.

Thanks in anticipation

kashmir